I'm trying to use alias in an operator overload to reduce typing, but what gets aliased is not what I expect. Tested in DMD v2.098.1-dirty on Windows plus whatever versions of DMD, GDC, and LDC I have installed on Linux. Thanks.

struct Broke
{
    double num;

    import std.traits : isNumeric;
    Broke opBinary(string op, T)(T rhs) if (is(T : Broke) || isNumeric!T)
    {
        static if ( is(T : Broke))
        {
            alias b = rhs.num;
            assert(&b != &this.num); //this fails
        }
        else
        {
            alias b = rhs;
        }

        static if (op == "+")
        {
            return Broke(num + b);
        }
    }
}

void main()
{
    import std.stdio;

    Broke foo = Broke(10);
    Broke bar = Broke(20);

    writeln(foo + 15);  //prints 25 as expected
    writeln(foo + bar); //prints 20
}

On Friday, 14 January 2022 at 17:48:41 UTC, kyle wrote:

void main()
{
    import std.stdio;

    Broke foo = Broke(10);
    Broke bar = Broke(20);

    writeln(foo + 15);  //prints 25 as expected
    writeln(foo + bar); //prints 20
}

I guess what you want to do is something like this:

struct Broke
{
    double num;

    Broke opBinary(string op)(Broke rhs)
    if(op == "+")
    {
      return Broke(this.num + rhs.num);/*
      this.num += rhs.num;
      return this;//*option 2*/
    }

    Broke opBinary(string op)(double rhs)
    if(op == "+")
    {
      return Broke(this.num + rhs);/*
      this.num += rhs;
      return this;//*option 2*/
    }
}

void main()
{
    import std.stdio;

    Broke foo = Broke(5);
    Broke bar = Broke(15);
    bar = foo + bar;    // #1 bar == Broke(20)

    writeln(foo + 15);  // #2 print ok => 20
    writeln(foo + bar); // #3 print ok => 25
}

So you don't need to use alias. If you want it the other way (option 2), turn off option 1 then option 2 will open automatically. Thus, same Broke() gets values: 20, 35 and 55.

regards,

• Salih